package di

import (
	"context"
	"fmt"
	"net/http"
	"os"
	"time"

	configimpl "git.dcentral.systems/toolz/goplt/internal/config"
	errorbusimpl "git.dcentral.systems/toolz/goplt/internal/errorbus"
	"git.dcentral.systems/toolz/goplt/internal/health"
	"git.dcentral.systems/toolz/goplt/internal/infra/database"
	loggerimpl "git.dcentral.systems/toolz/goplt/internal/logger"
	"git.dcentral.systems/toolz/goplt/internal/metrics"
	"git.dcentral.systems/toolz/goplt/internal/server"
	"git.dcentral.systems/toolz/goplt/pkg/config"
	"git.dcentral.systems/toolz/goplt/pkg/errorbus"
	"git.dcentral.systems/toolz/goplt/pkg/logger"
	"go.uber.org/fx"
)

// ProvideConfig creates an FX option that provides ConfigProvider.
func ProvideConfig() fx.Option {
	return fx.Provide(func() (config.ConfigProvider, error) {
		// Determine environment from environment variable or default to "development"
		env := os.Getenv("ENVIRONMENT")
		if env == "" {
			env = "development"
		}

		cfg, err := configimpl.LoadConfig(env)
		if err != nil {
			return nil, fmt.Errorf("failed to load config: %w", err)
		}

		return cfg, nil
	})
}

// ProvideLogger creates an FX option that provides Logger.
func ProvideLogger() fx.Option {
	return fx.Provide(func(cfg config.ConfigProvider) (logger.Logger, error) {
		level := cfg.GetString("logging.level")
		if level == "" {
			level = "info"
		}

		format := cfg.GetString("logging.format")
		if format == "" {
			format = "json"
		}

		log, err := loggerimpl.NewZapLogger(level, format)
		if err != nil {
			return nil, fmt.Errorf("failed to create logger: %w", err)
		}

		// Set as global logger
		logger.SetGlobalLogger(log)

		return log, nil
	})
}

// ProvideDatabase creates an FX option that provides the database client.
func ProvideDatabase() fx.Option {
	return fx.Provide(func(cfg config.ConfigProvider, lc fx.Lifecycle) (*database.Client, error) {
		dsn := cfg.GetString("database.dsn")
		if dsn == "" {
			return nil, fmt.Errorf("database DSN is not configured")
		}

		maxConns := cfg.GetInt("database.max_connections")
		if maxConns == 0 {
			maxConns = 25
		}

		maxIdleConns := cfg.GetInt("database.max_idle_connections")
		if maxIdleConns == 0 {
			maxIdleConns = 5
		}

		connMaxLifetime := cfg.GetDuration("database.conn_max_lifetime")
		if connMaxLifetime == 0 {
			connMaxLifetime = 5 * time.Minute
		}

		connMaxIdleTime := cfg.GetDuration("database.conn_max_idle_time")
		if connMaxIdleTime == 0 {
			connMaxIdleTime = 10 * time.Minute
		}

		dbClient, err := database.NewClient(database.Config{
			DSN:             dsn,
			MaxConnections:  maxConns,
			MaxIdleConns:    maxIdleConns,
			ConnMaxLifetime: connMaxLifetime,
			ConnMaxIdleTime: connMaxIdleTime,
		})
		if err != nil {
			return nil, fmt.Errorf("failed to create database client: %w", err)
		}

		// Register lifecycle hooks
		lc.Append(fx.Hook{
			OnStart: func(ctx context.Context) error {
				// Run migrations on startup
				if err := dbClient.Migrate(ctx); err != nil {
					return fmt.Errorf("failed to run database migrations: %w", err)
				}
				return nil
			},
			OnStop: func(ctx context.Context) error {
				return dbClient.Close()
			},
		})

		return dbClient, nil
	})
}

// ProvideErrorBus creates an FX option that provides the error bus.
func ProvideErrorBus() fx.Option {
	return fx.Provide(func(log logger.Logger, lc fx.Lifecycle) (errorbus.ErrorPublisher, error) {
		bufferSize := 100 // Can be made configurable
		bus := errorbusimpl.NewChannelBus(log, bufferSize)

		// Register lifecycle hook to close the bus on shutdown
		lc.Append(fx.Hook{
			OnStop: func(ctx context.Context) error {
				return bus.Close()
			},
		})

		return bus, nil
	})
}

// ProvideHealthRegistry creates an FX option that provides the health check registry.
func ProvideHealthRegistry() fx.Option {
	return fx.Provide(func(dbClient *database.Client) (*health.Registry, error) {
		registry := health.NewRegistry()
		
		// Register database health checker
		registry.Register("database", health.NewDatabaseChecker(dbClient))

		return registry, nil
	})
}

// ProvideMetrics creates an FX option that provides the Prometheus metrics registry.
func ProvideMetrics() fx.Option {
	return fx.Provide(func() *metrics.Metrics {
		return metrics.NewMetrics()
	})
}

// ProvideHTTPServer creates an FX option that provides the HTTP server.
func ProvideHTTPServer() fx.Option {
	return fx.Provide(func(
		cfg config.ConfigProvider,
		log logger.Logger,
		healthRegistry *health.Registry,
		metricsRegistry *metrics.Metrics,
		errorBus errorbus.ErrorPublisher,
		lc fx.Lifecycle,
	) (*server.Server, error) {
		srv, err := server.NewServer(cfg, log, healthRegistry, metricsRegistry, errorBus)
		if err != nil {
			return nil, fmt.Errorf("failed to create HTTP server: %w", err)
		}

		// Register lifecycle hooks
		lc.Append(fx.Hook{
			OnStart: func(ctx context.Context) error {
				// Start server in a goroutine
				go func() {
					if err := srv.Start(); err != nil && err != http.ErrServerClosed {
						log.Error("HTTP server error",
							logger.String("error", err.Error()),
						)
					}
				}()
				return nil
			},
			OnStop: func(ctx context.Context) error {
				return srv.Shutdown(ctx)
			},
		})

		return srv, nil
	})
}

// CoreModule returns an FX option that provides all core services.
// This includes configuration, logging, database, error bus, health checks, metrics, and HTTP server.
func CoreModule() fx.Option {
	return fx.Options(
		ProvideConfig(),
		ProvideLogger(),
		ProvideDatabase(),
		ProvideErrorBus(),
		ProvideHealthRegistry(),
		ProvideMetrics(),
		ProvideHTTPServer(),
	)
}

// RegisterLifecycleHooks registers lifecycle hooks for logging.
func RegisterLifecycleHooks(lc fx.Lifecycle, l logger.Logger) {
	lc.Append(fx.Hook{
		OnStart: func(_ context.Context) error {
			l.Info("Application starting",
				logger.String("component", "bootstrap"),
			)
			return nil
		},
		OnStop: func(_ context.Context) error {
			l.Info("Application shutting down",
				logger.String("component", "bootstrap"),
			)
			return nil
		},
	})
}